Alkalinization Is Ineffective for Severe Hyperkalemia in Nonnephrectomized Dogs

Abstract

Objective: ' To determine whether alkalinization with sodium bicarbonate (NaHCO,) in near-lethal hyperkalemia either lowers potassium (K) rapidly or shortens duration of cardiac conduction disturbances. Methods: A controlled canine laboratory investigation of 3 treatments for severe hyperkalemia. Conditioned dogs (n = 8; 17-30 kg) received, in random order, 2 mmolkg of each of 3 treatments (matched in sodium and water) in separate experiments 2 1 week apart: 1.05% NaHCO, over 60 minutes (infusion therapy); 8.4% NaHCO, over 5 minutes, then 14 mL/kg sterile water over 55 minutes (bolus therapy); 8.4% NaCl over 5 minutes, then 14 mwkg sterile water over 55 minutes (saline therapy). Prior to administering one of the above therapies, the animals were anesthetized with 0.5-2.5% isoflurane and ventilated to maintain a normal Pcoz. After 30 minutes of equilibration, 2 mmol/kg/hr (loading dose) of a 2-mmoVmL KC1 solution was given until idioventricular or relative junctional bradycardic dysrhythmias were sustained for 15 minutes. Then KC1 was decreased to 1 mmol/kg/hr (maintenance dose) for 2 hours and 45 minutes. Treatment was begun after 45 minutes of maintenance KCI infusion. Results: The pretreatment K level (all studies) was 9.06 2 0.82 mmoVL (mean 2 SD). Although the mean K level decreased more after saline therapy than after bolus therapy at every time, differences were neither statistically significant nor clinically important during the first 30 minutes. The means of the differences in decreases (saline minus bolus) were small, 0.26 (95% CI, -0.48 to 1.00) at 15 minutes, 0.16 (95% CI, -0.67 to 0.98) at 30 minutes. Dysrhythmia duration was shorter with bolus therapy than for saline therapy in only 1 of 5 dogs ( p = 0.38). Conclusions: Hypertonic saline bolus lowered plasma K as effectively as NaHC03 bolus in this animal model within the first 30 minutes. Clinically meaningful decreases due to alkalinization alone within 30 minutes are unlikely.

Effects of Alkalinization and Rehydration on Plasma Potassium Concentrations in Neonatal Calves with Diarrhea

“…This is particularly based on the results of studies in dogs with experimentally induced hyperkalemia24 and human patients with end‐stage renal disease25, 26 where alkalinization after intravenous administration of sodium bicarbonate was reported to be ineffective in lowering blood K + concentrations. However, it was discussed that the plasma potassium‐lowering effect of sodium bicarbonate depends on the presence of a metabolic acidosis and more importantly on the degree of intracellular acidosis 22.…”

Pathogenesis and therapy of non-oliguric hyperkalaemia of the premature infant

“…In hyperkalaemic animals, an intravenous bolus of hypertonic saline lowered serum K + as effectively as a sodium bicarbonate bolus (2 mmol/kg) within the first 30 min [26]. The authors concluded that clinically significant decreases in serum K + due to alkalinisation alone within 30 min are unlikely.…”

Letter to the Editor

“…Several investigations have shown little or no benefit to alkalinization for emergent treatment of hyperkalemia 2, 3, 4, 5. Kaplan et al 1997 JL.…”

“…Kaplan et al 1997 JL. (The hyperkalemia research group) investigated the efficacy of emergency alkalinization in non‐nephrectomized dogs with K + induced cardiac conduction abnormalities 5. The latter group used a control crossover study giving K + loads (mean ± SD pre‐treatment K + level of 9.06 ± 0.82 mmol/L), and comparing various treatments matched with respect to sodium and water content.…”